The present invention relates to a process for the manufacture of human mononuclear phagocytic leukocytes, to a culture of the cells obtained thereby and to the uses thereof.
Healing of injured tissue is a complex natural process based on the synchronized interaction between many molecular and physiological factors. An effective inflammatory response is one of the principal elements inducing regeneration and repair of damaged tissue. This is one of the earliest and most crucial reactions of tissues with regenerative capacity. The macrophages, which are recruited and further activated in situ, are key agents in the initiating stages of an effective inflammatory reaction. The inflammatory reaction is an integral part of wound healing in all the tissues in the body.
Following axonal injury, neurons of the mammalian peripheral nervous system (PNS) have a greater capacity than the central nervous system (CNS) for axonal regeneration and macrophages were shown to play a key role in PNS axonal regeneration (Schwartz et al., 1989, FASEB J., 3:2371-2378).
The mammalian CNS shows a poor capacity for axonal regeneration following axonal injury. The difference between axonal regeneration in the CNS and PNS seems to be due mainly to the cellular environment of the neurons than to the neurons themselves. Following neuronal injury, the Schwann cells that surround PNS neurons are modulated so as to become permissive or supportive for axonal regeneration, while the astrocytes, oligodendrocytes and microglia that surround CNS neurons do not show such modulation and remain unsupportive or inhibitory for axonal regeneration.
Differences in the post-injury inflammatory response are correlated with this lack of modulation. In particular, the accumulation of mononuclear phagocytes in response to CNS injury is delayed and limited in comparison with the response to injury in the PNS.
In the CNS, the inflammatory reaction is decreased, at least partly, due to the relative ineffectiveness of resident tissue macrophages (microglia). This deficit is further enhanced by the inability of blood-borne monocytes to enter the CNS and to act as they normally do in any other injured tissue in need of wound healing.
In U.S. Pat. Nos. 5,800,812, 6,117,424 and 6,267,955, all assigned to the same applicant of the present application, each and all of these patents being herein incorporated by reference as if fully disclosed herein, methods and compositions have been disclosed for the use of allogeneic mononuclear phagocytes to promote axonal regeneration in the CNS of a mammal. These patents describe methods for the isolation and culture of monocytes isolated from peripheral blood from adult Sprague-Dawley rats, and for the stimulation of the isolated monocytes by coincubation with syngeneic rat sciatic or optic nerve segments or by culture with medium conditioned by syngeneic rat sciatic nerve or optic nerve. The stimulated monocytes were then assayed for phagocytic activity and/or nitric oxide production and administered to rats that have been subjected to optic nerve transection at or near the site of injury.